I'll echo the check for rust. DO spend time under the vehicle and poke around. Remove panels if necessary. Check, check twice, especially under the doors and sills. Look hard at the subframe.

I just found three horrible spots in a rear tire well on one of my w124s. They really looked fine to my untrained eye. While changing the pads and rotors, I gave one of the small bubbles a little push, near the rubber grommet. The whole thing fell through. Now I have three holes the size of my fist in one well.

It sounds like a deal, but I'm really learning the hard way that if you have even semi-high standards, there is no such thing as a cheap Mercedes.